This invention relates to a tilt and trim unit for an outboard drive propulsion system and more particularly to an improved hydraulic arrangement for such applications wherein popping up is permitted when underwater articles are struck but the entire range of such movement is limited in a way wherein shocks at the end of travel are reduced.
Hydraulically operated units of this type are well known and frequently employ a hydraulic system for effecting not only trim adjustment during running operation, but also rapid tilt up to an out of the water position for trailering or servicing. As noted above these units frequently incorporate, generally in their trim portion, a shock absorbing arrangement that permits the propulsion unit to pop up when an underwater obstacle is struck and return to their trim adjusted position after the obstacle is cleared. The shock absorbing function is also calibrated to resist popping up when operating in reverse.
A typical type of such devices is shown in Japanese Published Application, number JP 07-69289, published Mar. 14, 1995. However if the underwater article is struck with sufficient force, the stroke of the shock absorbing piston can easily be insufficient and the resulting direct contact of the elements can cause damage. Stiffening of the shock absorbing action is not really an acceptable solution.
It is therefore a principal object of this invention to provide an improved hydraulic arrangement for such applications wherein popping up is permitted when underwater articles are struck but the entire range of such movement is limited in a way wherein shocks at the end of travel are reduced.